Spectroscopic study of dinitrophenol herbicide sorption on smectite
Spectroscopic study of dinitrophenol herbicide sorption on smectite
复制标题
DOI：
10.1021/es025760j
复制
发表时间：
2002-12-01
影响因子：
11.4
通讯作者：
De Oliveira, MF
中科院分区：
文献类型：
--
作者：
Johnston, CT;Sheng, G;De Oliveira, MF
采用红外光谱、高效液相色谱和量子化学方法研究了蒙脱石对4，6-二硝基邻甲酚（DNOC）和4，6-二硝基仲丁基苯酚（DINOSEB）两种二硝基酚类除草剂的吸附。DNOC和DINOSEB对蒙皂石表面的高亲和力归因于与可交换阳离子的位点特异性相互作用以及与硅氧烷表面的非特异性范德华货车相互作用。zetanu（asym）（NO）和nu（sym）（NO）的振动模式的位置被扰动的可交换阳离子与碱金属和碱土金属阳离子作为离子势的函数发生类似的变化。阳离子诱导的NO2基团的振动带的变化表明，可交换的金属阳离子配位到-NO2基团。量子化学方法预测的nu（sym）（NO）带的红移和相应的nu（sym）（NO）模式的蓝移，实验观察到。蒙脱石表面本身的性质并没有强烈影响吸附的DNOC或DINOSEB的振动模式的基础上的比较DNOC吸附到三个不同的蒙脱石（K-SWy-2，K-SAz-1，和K-SHCa-1）。用修正的比尔定律定量研究了DNOC和DINOSEB在K-SWy-2蒙皂石上的红外光谱。红外光谱法测得的吸附等温线与高效液相色谱法测得的等温线吻合较好。吸附在K-SWy-2蒙皂石上的DNOC的摩尔吸光系数值为1.43 x 10（7）cm（2）/mol，与文献中硝基芳烃的值（平均值为1.72 x 10（7）0.3 cm（2）/mol）非常一致。基于该值，确定了使用FTIR方法的检测限，其类似于5 μ g（DNOC）g（粘土）。这两个观察结果（吸附等温线和摩尔吸光系数）提供了宏观吸附结果和FTIR光谱之间的直接联系。
Sorption of two dinitrophenolic herbicides, 4,6-dinitro-o-cresol (DNOC) and 4,6-dinitro-2-sec-butylphenol (DINOSEB) to smectite was studied using FIR, HPLC, and quantum chemical methods. The high affinity of DNOC and DINOSEB for smectite surfaces was attributed to site-specific interactions with exchangeable cations and nonspecific van der Waals interactions with the siloxane surface. The positions of the zetanu(asym)(NO) and nu(sym)(NO) vibrational modes were perturbed by the exchangeable cations with similar changes occurring for both alkali and alkaline earth cations as a function of ionic potential. The cation-induced changes to the vibrational bands of the NO2 groups indicate that exchangeable metal cations are coordinated to -NO2 groups. Quantum chemical methods predicted a red-shift of the nu(asym)(NO) band and a corresponding blue-shift of the nu(sym)(NO) modes, as was observed experimentally. The nature of the smectite surface itself did not strongly influence the vibrational modes of sorbed DNOC or DINOSEB on the basis of a comparison of DNOC sorbed to three different smectites (K-SWy-2, K-SAz-1, and K-SHCa-1). FIR spectra of DNOC and DINOSEB sorbed to a K-SWy-2 smectite were studied quantitatively using a modified form of Beer's law. The FTIR-derived sorption isotherm of DNOC sorbed to K-SWy-2 was in good agreement with the isotherm derived from HPLC measurements. The molar absorptivity value of DNOC sorbed to K-SWy-2 smectite was 1.43 x 10(7) cm(2)/mol in good agreement with literature values for nitroaromatics (average value of 1.72 x 10(7) 0.3 cm(2)/mol). On the basis of this value, the limit of detection using the FTIR method of similar to5 mug(DNOC) g(clay) was determined. These two observations (sorption isotherms and molar absorptivity) provide a direct link between the macroscopic sorption results and the FTIR spectra.